It is well-known that a human eye has horizontally 120-degree wide field of view, its visual acuity is the highest near a center on a retina, so-called fovea, and decreases rapidly towards periphery of the fovea. This means that the human eye has a quite superior function that can observe an environment in detail by quite small amount of information by changing a direction of gaze in combination with eye movement.
Recently, inspired from the abovementioned human eye function, a special wide-angle lens having a distribution of magnification similar to that of the human visual acuity (wide-angle fovea lens hereafter) has been invented (see Patent Literature 1, for example). This special lens is applicable to a commercially-available imaging device such as CMOS/CCD cameras. Using the wide-angle fovea lens, a user can observe the wide field of view without increasing the amount of visual information and, simultaneously, can observe a target in detail in the central region, i.e., an attention region having high resolution in the field of view. Thus, the wide-angle fovea lens is an optical lens system which is quite effective in the field of information and communication technology.